Mediterranean Red Bug Aggregation in Southern California

Subject: Is this an elm seed bug? Found in Southern CA Location: N Los Angeles County, Southern California December 14, 2014 5:26 pm Hi! I’ve been trying so hard to identify this bug, which just appeared in my back yard this year, maybe early summertime. I’m in north Los Angeles County (town is Littlerock), Southern CA. They’ve gone from lumbering in sort-of lines along the ground to huddling in large numbers around bushes and under wood or metal, to now huddling en masse in the crevices of one of my large chinese elm trees. I took pictures; they are black and red, similar it looks like in shape etc. to your photos of the elm seed bug, but the markings on my bugs seem a bit different. I have various birds living out back (goose, emu, peahen, guinea hen, and occasionally chickens) and am wondering if these bugs are beneficial to my plants and/or birds, or if they are harmful. So far they’re not in the house, but I’m a little worried that might change! I’d appreciate any help you can give me on identifying these cute little huddlers — hopefully they are the good kind! ( I have several more pictures, by the way – your site only allowed me 3 so I tried to pick out the best 3) Signature: Heidi Brooks

Mediterranean Red Bug

Dear Heidi, These are Mediterranean Red Bugs, Scantius aegyptius, a species that was introduced to Southern California several years ago in about 2009 and it finds our climate to its liking, so it is proliferating. Here is what the UC Riverside Center for Invasive Species Research states: “Damage: The literature contains very little information regarding the biology of S. aegyptius and Scantius species in general are not considered to be economically important species. In California, Scantius has been observed feeding on the developing seeds and stems of Knotweed (Polygonum spp.) and Malva (Malva parviflora). It is likely that S. aegyptius will feed on the seeds of several species of annual herbaceous plants. The most noticeable impact of S. aegyptius in California will likely be the presence of large numbers of nymphs and adults migrating from drying annual weeds into adjacent developed areas. These migrations consisting of thousands of individuals can be very conspicuous and lead to large aggregations on small patches of host plants causing concern to local residents who notice these obvious aggregations.” Though they pose no immediate threat to crops, native plants or animals, the presence of a non-native species in large numbers can have significant effects on native species by displacing them in an ecosystem.

Dear Heidi,The link you provided is for a Firebug, a different species in the same family. Again, your species is Scantius aegyptius and you can find more information on BugGuide. When we first posted images of the Mediterranean Red Bug in 2010, we also incorrectly identified it as a very similar looking Firebug.

Wow! I didn’t notice that – the markings are so specific, with a triangle and 2 dots, I thought they were the same bug. I’ll have to do a little more research then, I think. It’s been difficult to find much about these insects, but at least I know that they don’t seem harmful to my plants or people. Thanks again — your responses mean a lot to me! Cheers, Heidi